Objectives - This research is directed to a study of the structure and biosynthesis of the glycoproteins on the surface of normal and transformed cells that bind plant lectins. The specific questions to be answered are: (a) What are the structures of the carbohydrate units at the binding sites? (b) Are the binding sites identical in normal and transformed cells? (c) What is the mechanism of the biosynthesis of the saccharide moieties of these glycoproteins? (d) What are the activities of the enzymes involved in the biosynthesis of cell envelope glycoproteins? Their specificities in regard to glycosyl donor and acceptor? Their location in the cell? How do normal and transformed cells differ in regard to the above? Approach - The basic approach has been to identify a number of low molecular weight compounds that serve as exogenous acceptors for mannosyltransfer by intact cells and cell free preparations. The products formed will be characterized and the structures of the most active acceptors will be determined. These results will be compared with products formed by mannosyltransfer to endogenous by the same enzyme preparations and with lectin binding glycoproteins isolated from the cell surface.